import {getLine} from "./utils_line.js"

// A Pos instance represents a position within the text.
export function Pos(line, ch, sticky = null) {
    if (!(this instanceof Pos)) return new Pos(line, ch, sticky)
    this.line = line
    this.ch = ch
    this.sticky = sticky
}

// Compare two positions, return 0 if they are the same, a negative
// number when a is less, and a positive number otherwise.
export function cmp(a, b) {
    return a.line - b.line || a.ch - b.ch
}

export function equalCursorPos(a, b) {
    return a.sticky == b.sticky && cmp(a, b) == 0
}

export function copyPos(x) {
    return Pos(x.line, x.ch)
}

export function maxPos(a, b) {
    return cmp(a, b) < 0 ? b : a
}

export function minPos(a, b) {
    return cmp(a, b) < 0 ? a : b
}

// Most of the external API clips given positions to make sure they
// actually exist within the document.
export function clipLine(doc, n) {
    return Math.max(doc.first, Math.min(n, doc.first + doc.size - 1))
}

export function clipPos(doc, pos) {
    if (pos.line < doc.first) return Pos(doc.first, 0)
    let last = doc.first + doc.size - 1
    if (pos.line > last) return Pos(last, getLine(doc, last).text.length)
    return clipToLen(pos, getLine(doc, pos.line).text.length)
}

function clipToLen(pos, linelen) {
    let ch = pos.ch
    if (ch == null || ch > linelen) return Pos(pos.line, linelen)
    else if (ch < 0) return Pos(pos.line, 0)
    else return pos
}

export function clipPosArray(doc, array) {
    let out = []
    for (let i = 0; i < array.length; i++) out[i] = clipPos(doc, array[i])
    return out
}
